Significant Accounting Policies - Narrative (Details) person in Millions, patient in Millions, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($) person building clinic patient state	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) person building clinic patient Segment state	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)		Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)
Significant Accounting Policies [Line Items]
Number of pharmacy plan members | person	103		103
Number of patients served per year | patient	1		1
Number of reportable segments | Segment			4
Allowance for credit losses	$ 342		$ 342					$ 319
Health insurer fee	248		519
Related party transaction, expenses from transactions with related party	3	$ 2	23	$ 12
Related party transaction, other revenues from transactions with related party	22	27	$ 43	52
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member		us-gaap:AccountingStandardsUpdate201602Member
Change in Accounting Principle, Accounting Standards Update, Transition Option Elected [Extensible List]			cvs:AccountingStandardsUpdate201613ModifiedRetrospectiveMember
Cumulative adjustment to retained earnings as a result of new accounting standard adoption	$ 68,355	61,599	$ 68,355	61,599	$ 58,543		$ 65,474	64,170	$ 60,006
Heartland Healthcare Services
Significant Accounting Policies [Line Items]
Number of states in which entity operates | state	4		4
Retail/ LTC
Significant Accounting Policies [Line Items]
Number of stores | building	9,900		9,900
Number of walk in medical clinics | clinic	1,100		1,100
Health Care Benefits
Significant Accounting Policies [Line Items]
Number of people served through health insurance products and related services | person	34		34
Retained Earnings
Significant Accounting Policies [Line Items]
Cumulative adjustment to retained earnings as a result of new accounting standard adoption	$ 48,768	$ 43,136	$ 48,768	$ 43,136	40,911		$ 46,455	45,108	$ 41,859
Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Cumulative adjustment to retained earnings as a result of new accounting standard adoption					178	[1]		(3)
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Significant Accounting Policies [Line Items]
Cumulative adjustment to retained earnings as a result of new accounting standard adoption					$ 178	[1]		$ (3)

[1] Reflects the adoption of Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842), which resulted in an increase to retained earnings of $178 million during the three months ended March 31, 2019.